Chemical oxygen generators are well known and are used for a variety of purposes, such as for example providing oxygen to the face masks stored within a housing located above each passenger and crew station in an aircraft as shown in U.S. Pat. No. 3,536,070. These chemical oxygen generators typically are provided with an oxygen liberating composition such as a chlorate or a perchlorate which generates oxygen when progressively decomposed after ignition, the oxygen generating composition being disposed within an insulated canister. The composition further may include a metal powder such as iron or carbon for burning and supplying part of the heat needed for combustion, a binder such as inorganic glass fibers for holding the mass together and aiding in the even decomposition of the chlorate or perchlorate, and a peroxide for chemically eliminating after start up the traces of chlorine gas released during thermal breakdown of the chlorate or perchlorate. These compositions are generally called chlorate candles, the candles being disposed within an insulated metal housing. In addition, as shown in U.S. Pat. No. 3,756,785 a chemical and mechanical filter is customarily provided at the discharge portion of the chemical oxygen generator for filtering out airborne particles, vapors and gases such as carbon monoxide. The filtering material typically includes hopcalite which is a well known specially prepared mixture of manganese dioxide and copper oxide in granular form which converts carbon monoxide into carbon dioxide. As most prior art chemical oxygen generators also discharge some free chlorine, the hopcalite also acts as a chlorine scrubber or getter. While hopcalite is an effective chlorine scrubber at relatively low volumes of air flow and low concentrations of chlorine, it is not effective at high flow rates and high concentrations. Also, normally hopcalite will outgas chlorine at high temperatures. With the development of a new series of chemical oxygen generators which exhibit higher oxygen flow than prior chemical oxygen generators, there is a requirement for a more effective chlorine getter. This is particularly true since the new series of chemical oxygen generators generate a large volume of chlorine in the range of 2000-3000 ppm during the first 30 seconds after activation.
It has been known in the past that activated carbon when coated with sodium hydroxide, as shown in U.S. Pat. No. 4,215,096 and granular pumice also when coated with sodium hydroxide, as shown in U.S. Pat. No. 2,442,356, serve as chlorine getters. However, while sodium hydroxide coated activated charcoal is a very efficient chlorine getter, activated charcoal is not suitable for use in an oxygen generator of the type referred to. Thus, when activated charcoal was tried in such a generator, the activated charcoal actually started to burn, causing a burn through in the stainless steel housing of the generator. The sodium hydroxide pumice was also tested and gave unacceptable test results. A hopcalite sold under the trade name of Carulite 200 by the Carus Corporation was also attempted to be coated by sodium hydroxide. However, when the Carulite 200 was added to the sodium hydroxide water solution rapid boiling occurred, and breakdown of the Carulite resulted. The consistency of the Carulite after being added to the sodium hydroxide solution was that of a sludge. It is believed that the Carulite 200 brand of the hopcalite is produced by the acid method. When used in this specification, acid method hopcalite is hopcalite produced generally by that method disclosed by Lucile S. Mathieu-Levy in Ann. mines 138, 23-40 (1949), Chemical Abstracts 44, 4764f, wherein hopcalite-type catalysts is prepared from MnSO.sub.4, CuSO.sub.4, H.sub.2 SO.sub.4 and H.sub.2 O. Also, is hopcalite produced generally by that method disclosed by Etienne Cheylan in Mem. services chim. etat (Paris) 31, 299-303 (1944), Chemical Abstracts 40, 5986 wherein a hopcalite-type catalyst is prepared from Cu and Mn salts and an alk. carbonate, preferably (NH.sub.4).sub.2 CO.sub.3.